Title: Fertilizer trials on potatoes in North Florida
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 Material Information
Title: Fertilizer trials on potatoes in North Florida
Physical Description: Book
Creator: Hensel, D. R.
Publisher: Agricultural Research Center,
Copyright Date: 1974
 Record Information
Bibliographic ID: UF00076346
Volume ID: VID00001
Source Institution: University of Florida
Holding Location: University of Florida
Rights Management: All rights reserved by the source institution and holding location.
Resource Identifier: 144709709 - OCLC

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AGRICULTURAL RESEARCH CENTER
Hastings, Florida

Hastings Research Report PR-1975-4


OJUNG 6 v'


J Nov 1974

November 1974


Fertilizer trials on potatoes in North Florida
D. R. Hensel, Soils Chemist

During the last year, fertilizer costs have nearly doubled. This
coupled with other increases in production costs makes it important to
increase fertilizer efficiency. Tests conducted in 1974 provided in-
formation on this problem.

Test 1

Combination of fertilizer rates with sidedressing rates, and time of
application were applied to potatoes. A standard practice of 1875 Ibs
6-8-8/A at planting followed by 40-0-40 sidedressing at 4 weeks was the
control. Yield results are presented in Table 1. Sidedressings increased
yields in comparison to 1250 Ibs 6-8-8 with out sidedressing. No treat-
ment yielded significantly more than the control. Sidedressings at 4
weeks after planting were generally more effective than equivalent amounts
applied at 2 or 6 weeks after planting. A large, single application of
sidedressing at 4 weeks was just as effective as multiapplications.

Table 1. Response of potatoes to various combinations of fertilization
rates, sidedressing rates, and application dates-1974


Fertilizer Sidedressing date Yield
Lbs 6-8-8/A 2 weeks 4-~weeks 6 weeks Size A
cwt/A


1. 1875

2. 1250

3. 1250

4. 1250

5. 1250

6. 1250

7. 1250

8. 1250

9. 1250

10. 1250
11-12-74
250 copies


25-0-25

25-0-25

25-0-25


25-0-25

25-0-25

25-0-25

25-0-25


160


20-0-10

20-0-10


70-0-85


o70-4o8


70-0-85







Test II

In general potato soils which have been in production over a period
of several years tend to show high readings of phosphorus by soil test
methods. Tests have shown that a response to phosphorus could be obtained
on these soils. However, recently with the increased cost of phosphorus
the practice of using high amounts is questioned. Therefore this test
was conducted to determine the response of phorphorus in combination with
various rates of nitrogen and potassium.
Potatoes were fertilized at planting with three rates each of nitrogen,
phosphorus and potassium in a factorial design during 1974. The pound per
acre rates were: Nitrogen 20, 80 and 140; Phosphorus (P205) 0, 75 and 150;
Potassium(K20)100, 150 and 200.
There was yield response to both nitrogen and phosphorus rates. How-
ever, a significant intersection indicates that the response was not the
same at each level of nitrogen. This is shown clearly in Table 2. Increasing
the rate of phosphorus at low levels of nitrogen did not influence potato
yields. However, at highest rate of nitrogen application a yield increase
was noted as phosphorus was increased. Evidently phosphorus was not a
limiting factor at the low nitrogen rates. At the high nitrogen rate
phosphorus became limiting and gave a response. Under the conditions of
this experiment yield differences between potassium levels (100, 150, and
200 lbs. K20/A) were not significant.

Table 2. Yield response of potatoes to three rates of nitrogen and
phosphorus-1974


Phosphorus Nitrogen rate-lb/A
Rate-lb/A


20 80 140

0 cwt/A

0 68 154 156

75 69 151 174

150___ 71 158 203



N** NL**, NQ**, P**, PL ** PQ**, N'P**






PR-1975-4


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